The present invention relates to a body mount for securing a part to a frame, and more particularly, to a vibration absorbing mount for securing an automobile body to a frame.
It is common in the automotive industry to secure and support an automobile body on its frame using body mounts having resilient insulators adapted to insulate the body against vibrations and shocks. Typical such body mounts are disclosed in U.S. Pat. Nos. 3,809,427, 3,622,194, 3,193,237 and 3,218,101. Those patents disclose upper and lower insulators, formed as cylinders with an aperture along their central axis, positioned on opposite sides of a horizontal frame portion. The mount comprises an upper retainer or spacer having a base and a tubular extension, and a lower retainer or thimble also having a base and a tubular extension. The upper and lower insulator cylinders are received around the respective tubular extensions. One of the tubular extensions includes at least a portion of its length sized to be received within the other tubular extension.
In use, the upper and lower parts of the mount, e.g. the spacer and thimble and the corresponding insulator, are placed on opposite sides of a support. For example, when used as a vehicle body mount, these parts would be located in alignment with an aperture in a frame. It is then necessary to hold these parts so assembled temporarily, while the vehicle body is placed on the several mounts, and the retaining bolts are passed through an aperture in the vehicle body, through the combined parts of the mount, and secured. The nut for securing such bolt may be part of the mount thimble.
To retain the so-assembled mount parts in place on the frame, a fixture has been used to pre-compress the insulators and to force the lower tubular extension into the upper tubular extension. In the system disclosed in said U.S. Pat. No. 4,809,427 a portable ram is then used to flare the end of the lower or thimble tube outwardly around a shoulder formed in the spacer tube. In the other patents mentioned, interengaging parts on (or associated with) the telescoped tubes act to hold them together when the mount is compressed by a workman. With the body then in position such that its openings are aligned with the openings through the mount tubes, a bolt is inserted therein and threaded into a weld nut or equivalent to secure the vehicle body on its frame.
However, the fixtures must be adapted to prevent rotation of the tubular members during bolt tightening to ensure the proper mating of the tubular members. The use of such a fixture greatly increases the cost of tooling, the number of assembly steps required, and the assembly time. U.S. Pat. Nos. 4,720,075 and 4,783,039 disclose improvements in such body mounts in which the two telescoping tubes are provided with mutually engaging polygonal walls which prevent relative rotation between the spacer and thimble.
What is needed, therefore, is an automobile body mount in which the lower insulator and the lower retainer are held in place without the need for a fixture, such that the body mount automatically engages and supports the lower insulator and the lower retainer when the retainers are moved toward one another during assembly. Further, a body mount is needed which includes means for preventing relative rotation between upper and lower retainers as well as between the retainers and the structure to which the body mount is attached.